Hydraulic excavator with integrated magnetic cross-beam

ABSTRACT

The present disclosure relates to a hydraulic excavator comprising a magnet attached to its stem or an attached magnetic cross-beam, in which the power of the magnets is adjustable, wherein it includes a safety control such that the magnetic force of the respective magnets is increased upon taking up a load and upon leaving a safety zone around the load take-up point, the travel speed of the excavator being switchable at the same time from a reduced value during load take-up to an increased speed.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to German Utility Model Application No. 20 2005 016 489.5, filed Oct. 20, 2005, which is hereby incorporated by reference in its entirety for all purposes.

FIELD

The present disclosure relates to a hydraulic excavator.

BACKGROUND AND SUMMARY

For taking up magnetic workpieces, such as cut sheets, it is known already to provide cranes, such as gantry cranes, with magnetic load take-up means. These magnetic load take-up means can comprise single magnets or magnetic cross-beams with a plurality of magnets. Such magnetic load take-up means are so-called loose load take-up means for cranes. In this respect, the standard EN 13155 exists, which requests a twofold safety of the material taken up before dropping the same. When using magnetic load take-up means in cranes, this leads to the fact that when taking up a load, the magnet of the magnetic load take-up means is initially only switched on with reduced power. The load taken up then is initially lifted slowly. When the load has been moved away from the load take-up point at least over a certain distance X, the crane provides a signal to the magnet control which then increases its power to twice the magnetic force. The twofold safety as requested by the standard EN 13155 is achieved thereby. In this condition, the travel speed of the crane can be increased.

Magnetic load take-up means are also used in excavators. It is known already to attach a cross-beam with magnets to the stem of an excavator. In the known embodiment of the hydraulic excavator with integrated magnetic cross-beam, the increase of the magnetic force upon load take-up is effected on the part of the excavator operator. During load take-up, a reduced force is initially applied onto the magnets of the magnetic cross-beam, as long as the excavator operator presses an On key. The load then is lifted slowly by the excavator operator. Upon overtravelling a distance estimated by the excavator operator, the same releases the On key, whereby the magnetic force is increased. This manual control of the magnetic force does, however, not exclude operating errors.

Therefore, it is the object underlying the present disclosure to provide a generic hydraulic excavator in which an automatic safety control is implemented.

In accordance with the present disclosure, this object is solved by a hydraulic excavator as described herein. Accordingly, a hydraulic excavator includes a magnet attached to a stem or a magnetic cross-beam attached to a stem, which comprises a plurality of magnets. The power of each of the magnets is adjustable. The inventive safety control of the hydraulic excavator is effected such that the magnetic force of the respective magnets is increased by taking up a load and upon leaving a safety zone around the load take-up point. Upon leaving the safety zone, which is formed spherically around the load take-up point, the travel speed of the excavator at the same time becomes switchable from a reduced value during load take-up to an increased speed, generally the normal speed.

By means of a hydraulic excavator which includes a corresponding safety control in accordance with the present disclosure, operating errors can be avoided and the standard EN 13155, which requests the twofold safety of the material taken up before dropping the same, can safely be observed without the risk of human operating errors, although the individual movements of the hydraulic excavator are activated by the excavator operator and, in contrast to a crane, are not translated by a simple electric control.

Further, in some embodiments, the safety zone starting from the take-up point of the load to be taken up by means of the magnet can be determined via sensors in that the travel distance of the load upon switching on the magnets can be determined by the sensors. In the crane control it is thus determined when the magnets are switched on. At this time, the position of the respective sensors is determined. Subsequently, the change in position by the sensors is monitored over time. Upon leaving a safety zone extending spherically around the take-up point, the magnets are switched to full load, which corresponds to the twofold safety.

Preferably, there are provided angle, inclination and/or displacement sensors for determining the travel distance.

An angle sensor can be provided for receiving the angular position α between stem and boom, and an inclination sensor can be provided for determining the boom inclination β.

In addition, an angle sensor can be provided for determining the angle of rotation γ of the uppercarriage.

When the hydraulic excavator is also displaced upon taking up the load, a displacement sensor can advantageously be provided for detecting the travel distance.

BRIEF DESCRIPTION OF THE FIGURES

Further features, details and advantages of the invention will be explained in detail with reference to an embodiment illustrated in the drawing. The only Figure (FIG. 1) schematically shows an excavator with attached magnetic cross-beam.

DETAILED DESCRIPTION

The hydraulic excavator 10 as shown in FIG. 1 includes a boom 12 to be inclined by the angle β and a stem 14 pivotally connected with said boom. The stem 14 can be swivelled with respect to the boom 12 by the angle α by means of a hydraulic cylinder 16. At the front end of the stem 14, there is provided a magnetic cross-beam 18 with two magnets 20 and 22. The angle γ is the angle of rotation of the uppercarriage 24 of the excavator about the slewing ring 26.

In broken lines, the stem 14′ and the magnetic cross-beam 18′ are shown at a time at which a load is taken up by the magnets 20′ and 22′. At this time, the pivot point 28 of the magnetic cross-beam 18′ on the stem 14′ is in a defined position. This position is detected by correspondingly detecting the angles α, β, γ in the excavator control.

Subsequently, the inventive safety control of the hydraulic excavator 10 detects a change in the angles α, β, γ and at the same time determines whether the radius “X” formed spherically around the starting point is left. As long as the pivot point 28 of the cross-beam 18′ lies within the spherical space with the radius X, the magnets 20′ and 22′ are subject to a reduced magnetic force, which is sufficient for taking up the load. During this working phase, the excavator can only be moved with a reduced speed. Upon leaving the safety radius “X”, however, the magnetic force of the magnets 20 and 22 is increased substantially, preferably doubled. The magnetic system communicates this power upshift to the control. Thereupon, the excavator can again be moved with full travel speed. If the excavator control does not receive this signal of the magnetic system comprising the magnets 20 and 22, the excavator still can only be moved with the reduced travel speed. 

1. A hydraulic excavator comprising a stem, a magnet coupled to the stem, in which the power of the magnets is adjustable, and a safety control such that the magnetic force of the respective magnets is increased upon taking up a load and upon leaving a safety zone around the load take-up point, wherein the travel speed of the excavator can at the same time be switched from a reduced value during load take-up to an increased speed.
 2. The hydraulic excavator as claimed in claim 1, wherein the safety zone starting from the take-up point of the load to be taken up by means of the magnets can be determined via sensors in that the travel distance of the load upon switching on the magnets can be determined by the sensors.
 3. The hydraulic excavator as claimed in claim 2, wherein there are provided angle, inclination and/or displacement sensors for determining the travel distance.
 4. The hydraulic excavator as claimed in claim 3, wherein an angle sensor is provided for taking up the angular position α between stem and boom, and an inclination sensor is provided for determining the boom inclination β.
 5. The hydraulic excavator as claimed in claim 4, wherein the angle sensor is provided for determining the angle of rotation γ of the uppercarriage.
 6. The hydraulic excavator as claimed in claim 1, wherein a displacement sensor is provided for detecting the travel distance of the hydraulic excavator.
 7. The hydraulic excavator of claim 1, wherein the magnet is coupled to the stem via an attached magnetic cross-beam.
 8. The hydraulic excavator of claim 1, wherein the magnet is attached to the stem. 